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1.
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Linked genes are
a. | genes that are found on the X (or less frequently the Y)
chromosome. | b. | genes that control two related traits, such as eye color and skin
color. | c. | genes that are located near each other on the same chromosome. | d. | genes that are found
in many different types of organisms. |
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2.
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Thomas Hunt Morgan is famous for his experimentation with fruit fly
genetics. He was able to determine experimentally that the genes for body color and wing size
seemed to be linked. How was he able to draw this conclusion?
a. | When he crossed a heterozygous (wild-type) fly with a double mutant (black body,
vestigial wings), a greater proportion of the offspring had the parental phenotype than would be
predicted by the Punnett square. | b. | When he crossed two dihybrid (heterozygous,
wild-type) flies, he saw a 9:3:3:1 phenotype ratio. | c. | When he crossed two double mutant (black body,
vestigial wings) flies, he saw the wild-type phenotype reappear in some of the
offspring. | d. | When he crossed a true-breeding (wild-type) fly with a true-breeding double mutant
(black body, vestigial wings), he saw 100% wild-type offspring. |
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3.
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Two parent pea plant have the following phenotypes: plant #1 has purple flowers
and green seeds and plant #2 has white flowers with yellow seeds. When crossed, they produce a
plant in the next generation that has purple flowers and yellow seeds. How would this offspring
be described?
a. | parental type | c. | crossover type | b. | recombinant type | d. | wild-type |
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4.
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Morgan’s fruit fly experiments showed that it is possible for some
offspring to show a different combination of traits than the parents. He determined that there
must be some process to allow this to happen. Later experiments showed this process to
be
a. | sex linkage. | c. | errors during meiosis. | b. | chromosomal
mutation. | d. | crossing
over. |
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5.
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Why is recombination and random fertilization important in the evolution of
organisms?
a. | it allows for the very quick reproduction of prokaryotes | b. | it results in
greater genetic variation for natural selection | c. | it increases the mutation
rate | d. | all of the above |
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6.
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How is a map unit defined?
a. | it is equal to the recombination frequency; 1% = 1 map unit | b. | it is measured as
the number of nucleotides between the end of one gene and the beginning of the
next | c. | it is measured as physical distance (usually in picometers) of the centromere to the
gene | d. | it is determined by the number of chromosomes that carry the
gene |
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7.
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How is it possible for genes on the same chromosome to behave as if they are
genetically unlinked?
a. | if it is on a sex chromosome | c. | if they are far enough
apart | b. | if it is a gene for a metabolic protein | d. | it is not
possible |
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